The study, conducted at the University of Auckland’s Liggins Institute in New Zealand, found that as a first-born child, your body will have greater difficulty absorbing sugars and higher daytime blood pressure than that of a child who has older siblings. There was a 21% drop in insulin sensitivity among first-born children, and this study was the first to document this.
For the study, 85 healthy children between the ages of 4 and 11 were measured for fasting lipid and hormonal profiles, height, weight and body composition. Researchers focused on children because puberty and adult lifestyle can affect insulin sensitivity. The results were that the 32 first-born children who participated in the study had a 21% reduction in insulin sensitivity and a 4 mmHg increase in blood pressure. However, the good news was that the older and only children tended to be taller and slimmer than their younger counterparts.
According to Wayne Cutfield, MBChB, DCH, FRACP, of the University of Auckland, ‘Although birth order alone is not a predictor of metabolic or cardiovascular disease, being the first-born child in a family can contribute to a person’s overall risk.’ The team surmised that the metabolic differences may be due to the physical changes in the mother’s uterus during her first pregnancy, which tends to increase the flow of nutrients to foetuses during subsequent pregnancies.
The findings of this research could have major implications worldwide. In many countries, especially China, family size is shrinking and a larger proportion of the population is made up of first-born children. This means you could see widespread cases of conditions like type 2 diabetes, coronary artery disease, stroke and hypertension. Cutfield concluded, ‘Our results indicate first-born children have these risk factors, but more research is needed to determine how that translates into adult cases of diabetes, hypertension and other conditions.’